基础学习总结（六）--getContentRolver()的应用、内容监听者ContentObserver

ContentResolver / getContentResolver()

 

外界的程序通过ContentResolver接口可以访问ContentProvider提供的数据，在Activity当中通过getContentResolver()可以得到当前应用的 ContentResolver实例。ContentResolver提供的接口和ContentProvider中需要实现的接口对应，具体可以查看API Doc，不过可以发现ContentResolver里面的方法很多都是final或者static的。在实际应用中，我们很少实现ContentResolver抽象类，更多时候通过getContentResolver()从一个Activity或其它应用程序组件的实现里获取一个ContentResolver：

短信的uri地址:"content:\\sms\"

 public class MainActivity extends Activity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

     }

     /*
      * 备份短信点击事件*/
     public void backupSms(View v){
         //1.查出所有短信
         Uri uri = Uri.parse("content://sms/");
         //通过上下对象的getContentRolver方法获得ContentResolver实例
         ContentResolver resolver = getContentResolver();
         //获得游标Cursor对象
         Cursor cor= resolver.query(uri, new String[]{"_id","address","date","type","body"}, null, null, null);
         if(cor!=null&&cor.getCount()>0){
             List<SmsInfo> list=new ArrayList<SmsInfo>();
             SmsInfo sms;
             while(cor.moveToNext()){
                 sms=new SmsInfo();
                 sms.setsId(cor.getInt(0));
                 sms.setAddress(cor.getString(1));
                 sms.setDate(cor.getLong(2));
                 sms.setType(cor.getInt(3));
                 sms.setBody(cor.getString(4));
                 list.add(sms);
             }
             cor.close();
             Log.w("MainActivity", "list中条数："+String.valueOf(list.size()));
             //2.存到本地
             writeToLocal(list);
         }

     }

     private void writeToLocal(List<SmsInfo> smslist){

         try {
             XmlSerializer srlz= Xml.newSerializer();//得到序列化对象
             /*动态获取sd卡地址
              * String state=Environment.getExternalStorageState();
             if(Environment.MEDIA_MOUNTED.equals(state)){
                 return;
             }
             File sdcardFile=Environment.getExternalStorageDirectory();
             File f=new File(sdcardFile,"sms.xml");*/
             FileOutputStream fos=new FileOutputStream("/mnt/sdcard/sms.xml");
             //将数据写入xml文本
             srlz.setOutput(fos, "utf-8");

             srlz.startDocument("utf-8", true);

             srlz.startTag(null, "SmsInfo");
             for (SmsInfo s : smslist) {
                 srlz.startTag(null, "sms");
                 srlz.attribute(null, "id", String.valueOf(s.getsId()));

                 srlz.startTag(null, "address");
                 srlz.text(s.getAddress());
                 srlz.endTag(null, "address");

                 srlz.startTag(null, "date");
                 srlz.text(String.valueOf(s.getDate()));
                 srlz.endTag(null, "date");

                 srlz.startTag(null, "type");
                 srlz.text(String.valueOf(s.getType()));
                 srlz.endTag(null, "type");

                 srlz.startTag(null, "body");
                 srlz.text(s.getBody());
                 srlz.endTag(null, "body");

                 srlz.endTag(null, "sms");
             }

             srlz.endTag(null, "SmsInfo");

             srlz.endDocument();

             Toast.makeText(this, "保存成功", 0).show();

         } catch (Exception e) {
             Toast.makeText(this, "保存失败", 0).show();
             e.printStackTrace();

         }
     }
 }

备份短信实例

添加外部读写权限与本地读取权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

<uses-permission android:name="android.permission.READ_SMS"/>

联系人的uri地址：

content://com.android.contacts/raw_contacts
content://com.android.contacts/data

 public class MainActivity extends Activity {

     private static final String TAG = "MainActivity";

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
     }

     private void printCursor(Cursor cursor) {
         if(cursor != null && cursor.getCount() > 0) {

             while(cursor.moveToNext()) {

                 int columnCount = cursor.getColumnCount(); // 列的总数

                 for (int i = 0; i < columnCount; i++) {
                     String columnName = cursor.getColumnName(i);    // 取对应i位置的列的名称
                     String columnValue = cursor.getString(i); // 取出对应i位置的列的值

                     Log.i(TAG, "当前是第" + cursor.getPosition() + "行: " + columnName + " = " + columnValue);
                 }
             }
             cursor.close();
         }
     }

     /**
      * 查询联系人
      * @param v
      */
     public void queryContacts(View v) {
         // 1. 去raw_contacts表中取所有联系人的_id
         Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");
         Uri dataUri = Uri.parse("content://com.android.contacts/data");

         Cursor cursor = getContentResolver().query(uri, new String[]{"_id"}, null, null, null);
 //        printCursor(cursor);
         if(cursor != null && cursor.getCount() > 0) {

             while(cursor.moveToNext()) {
                 int id = cursor.getInt(0);
                 // 2. 去data表中根据上面取到的_id查询对应id的数据.

                 //where语句
                 String selection = "raw_contact_id = ?";
                 //where语句需要的值
                 String[] selectionArgs = {String.valueOf(id)};
                     //                                                需要的字段
                 Cursor c = getContentResolver().query(dataUri, new String[]{"data1", "mimetype"},
                         selection, selectionArgs, null);
                 if(c != null && c.getCount() > 0) {

                     while(c.moveToNext()) {
                         String mimetype = c.getString(1);        // 当前取的是mimetype的值
                         String data1 = c.getString(0);        // 当前取的是data1数据

                         if("vnd.android.cursor.item/phone_v2".equals(mimetype)) {
                             Log.i(TAG, "号码: " + data1);
                         } else if("vnd.android.cursor.item/name".equals(mimetype)) {
                             Log.i(TAG, "姓名: " + data1);
                         } else if("vnd.android.cursor.item/email_v2".equals(mimetype)) {
                             Log.i(TAG, "邮箱: " + data1);
                         }
                     }
                     c.close();
                 }
             }
             cursor.close();
         }

     }

     public void addContacts(View v) {
         Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");
         Uri dataUri = Uri.parse("content://com.android.contacts/data");
         // 1. 在raw_contacts表中添加一个记录

         // 取raw_contacts表中contact_id的值
         Cursor cursor = getContentResolver().query(uri, new String[]{"contact_id"}, null, null, "contact_id desc limit 1");
         if(cursor != null && cursor.moveToFirst()) {
             int contact_id = cursor.getInt(0);
             contact_id ++;
             cursor.close();

             ContentValues values = new ContentValues();
             values.put("contact_id", contact_id);
             getContentResolver().insert(uri, values);

             // 2. 根据上面添加记录的id, 取data表中添加三条数据

             // 存号码
             values = new ContentValues();
             values.put("mimetype", "vnd.android.cursor.item/phone_v2");
             values.put("data1", "10086");
             values.put("raw_contact_id", contact_id);
             getContentResolver().insert(dataUri, values);

             // 存姓名
             values = new ContentValues();
             values.put("mimetype", "vnd.android.cursor.item/name");
             values.put("data1", "中国移动");
             values.put("raw_contact_id", contact_id);
             getContentResolver().insert(dataUri, values);

             // 存姓名
             values = new ContentValues();
             values.put("mimetype", "vnd.android.cursor.item/email_v2");
             values.put("data1", "10086@kengni.com");
             values.put("raw_contact_id", contact_id);
             getContentResolver().insert(dataUri, values);
         }

     }
 }

获取联系人

添加联系人的读写sd卡权限

<uses-permission android:name="android.permission.READ_CONTACTS"/>
<uses-permission android:name="android.permission.WRITE_CONTACTS"/>

ContentObServer应用：

1 首先创建一个ContentObserver的子类，然后实现里面的onChange方法，监听的Uri中的数据发生变化的时候，会调用onchange方法。

2 注册ContentObserver。

 public class MainActivity extends Activity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

         // 监听系统短信

         ContentResolver resolver = getContentResolver();

         // 注册一个内容观察者观察短信数据库
         resolver.registerContentObserver(Uri.parse("content://sms/"), true, new MyContentObserver(new Handler()));
     }

     /**
      * 内容观察者
      */
     class MyContentObserver extends ContentObserver {

         private static final String TAG = "MyContentObserver";

         public MyContentObserver(Handler handler) {
             super(handler);
         }

         /**
          * 当被监听的内容发生改变时回调
          */
         @Override
         public void onChange(boolean selfChange) {
             Log.i(TAG, "短信改变了");
             Uri uri = Uri.parse("content://sms/outbox");    // 发件箱的uri

             // 查询发件箱的内容
             Cursor cursor = getContentResolver().query(uri, new String[]{"address", "date", "body"}, null, null, null);
             if(cursor != null && cursor.getCount() > 0) {

                 String address;
                 long date;
                 String body;
                 while(cursor.moveToNext()) {
                     address = cursor.getString(0);
                     date = cursor.getLong(1);
                     body = cursor.getString(2);

                     Log.i(TAG, "号码: " + address + ", 日期: " + date + ", 内容: " + body);
                 }
                 cursor.close();
             }
         }
     }
 }